jhplot.math.num.root

Class BisectionRootFinder

java.lang.Object

jhplot.math.num.IterativeMethod

jhplot.math.num.root.BisectionRootFinder

public class BisectionRootFinder
extends IterativeMethod

The bisection method (1) for finding roots of functions.

For example, to find roots for sine, first a Function is defined:

 Function sine = new Function() {
    public double evaluate(double x) {
        return Math.sin(x);
    }}
 };
 

Then, a bisection root finder is created with the above function:

 BisectionRootFinder finder = new BisectionRootFinder(sine);
 

Lastly, locating roots is accomplished using the findRoot(double, double) method:

 // find the root between 3 and 4.
 double pi = finder.findRoot(3.0, 4.0);
 
 // find the root between -1 and 1.
 double zero = finder.findRoot(-1.0, 1.0);
 

References:

1. Eric W. Weisstein. "Bisection." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/Bisection.html

Constructor Summary

Constructors

Constructor and Description
BisectionRootFinder(Function f) Create a root finder for the given function.
BisectionRootFinder(Function f, int iterations, double error) Create a root finder for the given function.

Method Summary

Modifier and Type	Method and Description
double	findRoot(double min, double max) Find a root of the target function that lies in the interval [ min, max].
Function	getFunction() Access the target function.
void	setFunction(Function f) Modify the target function.

Methods inherited from class jhplot.math.num.IterativeMethod

getMaximumIterations, getMaximumRelativeError, iterate, setMaximumIterations, setMaximumRelativeError

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BisectionRootFinder

public BisectionRootFinder(Function f)

Create a root finder for the given function.

Parameters:

f - the target function.

BisectionRootFinder

public BisectionRootFinder(Function f,
                           int iterations,
                           double error)

Create a root finder for the given function.

Parameters:

f - the target function.

iterations - maximum number of iterations.

error - maximum relative error.

Method Detail

findRoot

public double findRoot(double min,
                       double max)
                throws NumericException

Find a root of the target function that lies in the interval [ min, max].

Parameters:

min - the lower bound of the search interval.

max - the upper bound of the search interval.

Returns:

a root that lies between min and max, inclusive.

Throws:

NumericException - if a root could not be found.

getFunction

public Function getFunction()

Access the target function.

Returns:

the target function.

setFunction

public void setFunction(Function f)

Modify the target function.

Parameters:

f - the new target function.